Phytochemical Screening, Proximate Compositions and Heavy Metal Concentrations of Four Commonly Sold Vegetables in Some Lagos Markets, Nigeria

Abstract

Leafy vegetables are part of African households and these vegetables are eaten for their nutritive and medicinal uses. Scarcity of the vegetables has increased the demands. However, environmental pollution is a challenge on their safety. Gongronema latifolium, Piper guineense, Lasianthera africana, Heinsia crinata vegetables obtained from different markets in Lagos, Nigeria. Phytochemical, proximate and heavy metal analyses of the vegetables were carried out.  These four vegetables were shown to be rich in nutrients. They also contained appreciable secondary metabolites- saponins, alkaloid etc. content of which may vary except terpenoids. However, mineral and heavy metal analyses revealed the ranges of K(29.43-68.09 mg/kg), Mg(26.33-28.41 mg/kg), Pb(0.01-0.03 mg/kg), Mn(2.44-21.84 mg/kg), Ag(0.01-0.24 mh/kg), Zn(0.54-1.34 mg/kg), Cd(0.01-0.02 mg/kg), Fe(2.17-3.92 mg/kg), Ni(1.22-1.46 mg/kg) and Na (1.84-4.32 mg/kg) in all the vegetables. These metals are within or below the W.H.O and other known world agencies’ permissible limits. Thus, the vegetables are safe for consumption as at the time of this research. However, despite the fact that the heavy metals’ concentration of the vegetables are within or below permissible limits, variation occurred in metallic compositions of the vegetables. Thus, this may serve as an indicator that the sources or locations in which these vegetables are grown before they are taken to markets should be monitored.